Heap leaching of gold was pioneered in the United States in 1973 at Placer Development's Cortez open pit in Nevada and proved on a larger scale at Pegasus Gold's Zortman Landusky mine in Montana. Although it is low cost, recovery rates average only sixty to seventy per cent, significantly less than with conventional milling.
Exposure is most likely to occur during mining, production, and transportation of mercury, as well as mining and refining of gold and silver ores. Mercury is commonly found in thermometers, manometers, barometers, gauges, valves, switches, batteries, and highintensity discharge (HID) lamps.
· In 2016, Peru declared a temporary state of emergency over widespread mercury poisoning in Madre de Dios, a jungle province rife with illegal mining. Nearly four in five adults in the area's capital city tested positive for dangerous levels of mercury, according to the Carnegie Institution for Science in Washington,
America's top ten power plants for mercury pollution: 1. Luminant Generation, Martin Lake Steam Electric Station Lignite Mine in Rusk County, Texas (1,501 lbs. of mercury emissions) 2. Southern Co., Gaston Steam Plant in Shelby, Alabama (1,244 lbs. of mercury emissions) 3.